FIG. 10 is a cross-sectional view of an input device including a button 21 movable in up and down used an information device for visually-challenged persons, and disclosed in Japanese Patent Laid-Open Publication No. 2001-7652. Button 21 moves upward and downward acording to up and down movement of up/down pin 25 which is moved by rotating ascend/descend gear 24 engaged with pinion 23 of motor 22. More specifically, screw portion 26 of up/down pin 25 is rotatably engaged to a central screw hole of ascend/descend gear 24. When ascend/descend gear 24 rotates, up/down pin 25 shifts in up and down directions by an interactive force caused by the screw hole of ascend/descend gear 24 and the screw portion cut on up/down pin 25, hence moving button 21. Pinion 23 of motor 22 is movable in right and left directions. Pinion 23 can be engaged with ascend/descend gear 24 and can be separated releasing the engaging. Switch 27 is activated with button 21.
In this conventional input device, since up/down pin 25 is engaged with ascend/descend gear 24 to be linked to gear 24, ascend/descend gear 24 and up/down pin 25 move together when button 21 is manually pressed. Therefore, immobile motor 22 and pinion 23 linked together serve as a resistive force against up and down movement of button 21 after motor 22 moves button 21 through pinion 23, affecting operability of button 21. In order to avoid it, a mechanism for releasing pinion 23 from ascend/descend gear 24 is necessary. A mechanism for moving pinion 23 in right and left directions to release the gears from each other has the input device be large and complicated.